I not a fan of "Lionchief", but I am a fan of "Lionchief Plus"!
In reality, it's hard to use one Legacy / TMCC remote to control multiple trains at the same time. You are constantly switching engine numbers adjusting the locomotives speed or functions if they are on the same track or approaching a crossover or turnout where multiple locomotive control is needed.
Having another "engineer" controlling his train, whether Legacy / TMCC or LionChief Plus is the ideal situation. This is a low cost way to get more 1:1 remotes to engines in one engineers hands. Adding another Legacy / TMCC will of course work, but it is very expensive.
Having the ability to still run conventional is a must for me, but of course I prefer command control when I have the choice.
What I would like to see in the future is some way to use Legacy to talk to a new box that would mimic the individual remotes so that you still can have your "universal" remote that can control anything (assuming there is a magic box in the system that can repeat the commands on the LionChief remotes frequencies for that engine).
It shouldn't be that hard to do, like having multiple channels for RC cars and planes. You would just tell Legacy to connect to a LionChief train you would program, and it would send signals to the new box which intern will send the correct LionChief signals to your train.
This would make everyone happy, and have all the bases covered.
For all I know, may be Lionel is already working on such a beast in the future...
Its not long before DCS talks to legacy now that it's opened, and Legacy in turn should be expanded through hardware to talk to these LionChief locomotives.
In the meantime, I always thought ideally, you want one remote per train for optimal control, and this does it.
I hope Lionel reads my post and considers this.